The present inventive subject matter relates to stunning and/or euthanization of laboratory fish using electric currents and the monitoring of the laboratory fish to prevent injury thereof.
Electrofishing involves the use of electric currents to attract and/or repel fish with the intent of creating aquatic barriers and/or to increase collection yields. It has been established that relatively small potentials that are impressed across the body of a fish invoke a flight reaction. Larger potentials result in the alignment of the fish with the electric current, or electrotaxis. Still larger potentials may result in electronarcosis and/or the complete euthanasia (e.g. tetany) of the fish. (See Introduction to Electrofishing, pages 24-26, Smith-Root, Inc. which is incorporated herein by reference).
Electrofishing has traditionally been used in freshwater lakes and streams and is the subject of U.S. Pat. Nos. 5,445,111; 5,327,854; 4,750,451; 4,672,967; 4,713,315; 5,111,379; 5,233,782; 5,270,912; 5,305,711; 5,311,694; 5,327,668; 5,341,764; 5,551,377; and 6,978,734 which are incorporated herein by reference. Also, electrofishing has been the used to stimulate yields of trawl net fishing as described in U.S. Pat. Nos. 3,110,978 and 4,417,301 which are also incorporated herein by reference. Furthermore, certain systems for controlling electricity in aquatic environments have been described in U.S. Pat. No. 5,460,123 which is incorporated herein by reference.
Also systems for monitoring small laboratory fish are described in U.S. Patent Publication 2006/0018833 which is incorporated herein by reference.
As is clear from the prior art, there is a considerable body of work associated with the electrification of large bodies of water to impress electric fields across larger fish, such as Salmon or Trout, as compared to smaller fish, which are typically found in a laboratory.
Prior art solutions and techniques that induce narcosis in fish include the addition of chemicals to the tank. The addition of chemicals to the tank water may make the fish temporarily motionless, but, such chemicals are expensive to use, may be toxic to the fish and/or the researcher, and may also interfere with experiment itself. Also, the use of chemicals to induce fish tenany may be unnecessarily complex and expensive requiring the training of specialized personnel. Other means of inducing fish euthanasia has been through the injection (e.g. bubbling) of carbon dioxide gas in a tank holding the target fish.
In certain situations, the experimenter may also wish to induce euthanasia in fish that reside in small bodies of water and/or laboratory tanks. Euthanasia should be induced in a manner to reduce any amount of pain to the fish.
It is also understood that the laboratory fish may have high commercial value as consequence of unique breeding, for example, the fish may be bred to with certain genetic abnormalities that are important to certain laboratory tests. The inadvertent death of these fish, as opposed to their temporary anesthesia, may deprive the research of important benefits.
Therefore, there is a need to have a portable unit that can euthanize with relatively low voltages. This portable unit not only has the aforementioned advantage of eliminating chemicals, but it also reduces the risk to the experimenter who may come into contact with the water and/or the operational electrodes.
There is also a need to have a portable unit that can euthanize with relatively low voltages that are species specific and/or test subject specific so that the
Therefore there is also a need to have a monitoring system to insure that a laboratory fish does not come into contact with an anode or a cathode to prevent potentially injurious shock.
Furthermore one of the problems encountered with the use of constant direct current (DC) fields is that a deposition layer appears on one of the electrodes. This deposition layer increases the resistance of the electrode during use which decreases its effectiveness. Therefore, it is desired to have a unit that minimizes the deposition layer on either of the electrodes during operation.
Therefore, what is desired is an apparatus to immobilize fish and place the fish in the states of narcosis, tetany, and/or euthanasia. It is also desired that this apparatus operate at relatively low voltage levels. It is also desired that the apparatus reduce the amount of deposition on either of the electrodes during operation.